DHS testing specialized plug to contain subway fires.

• Position: SECURITY BEAT

* Researchers at West Virginia University and the Pacific Northwest National Laboratory are developing a "tunnel plug" that would stop fires from spreading in underground train stations.

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The plug is essentially a giant beach ball that drops from the ceiling and inflates inside a subway tunnel. It seals off the entire passageway and, ideally, prevents smoke or fire from expanding.

The project also aims to protect against flooding, chemicals and other hazards, said the Department of Homeland Security's directorate for science and technology.

The tunnel plug program is funded by the homeland security advanced research projects agency within the Department of Homeland Security's science and technology directorate.

Researchers first tested much smaller plugs in a scale model transit tunnel. Based on those experiments, a design was selected for a full-scale device. A prototype was built and a model of a mass transit tunnel was constructed for further testing at West Virginia University last spring and summer.

More testing was done in August in an actual mass transit tunnel through a partnership with the Washington Metropolitan Area Transit Authority, which serves Washington, D.C. and the...